Improved furnace and apparatus for treating pyritous ores



J. FRETZ.

Ore Roaster.

Patented Sept. 20.1859

NITED STATES a'rnN'r OFFICE.

IMPROVED FURNACE AND APPARATUS FOR TREATING PYRITOUS ORES.

Specification formingpart of Letters Patent No. 25,5005 dated September20, 1859.

To aZZ whom it may concern Be it known that I, JOHN FRETZ, of Angel,Oalaveras county, State of California, have invented a new and ImprovedApparatus for Desulphurizing and Oarbonizing Pyrites; and I do herebydeclare the following to be a full, clear, and exact description of thesame, reference being had to the accompanying draw ings, and to theletters of reference marked thereon.

My invention consists in an apparatus, fully described hereinafter,whereby the desulphurizing and oxidizing of pyrites, through the agencyof heat, currents of air, and a jet or jets of steam, is so graduallyand efficiently accomplished that the removal of the valuable metalsfrom the pyrites by any amalgamating process is facilitated.

In order to enable others to make and use my invention, I will nowproceed to describe its construction and operation.

On reference to the accompanying drawings, which form a part of thisspecification, Figure l is a plan view of my improved apparatus foroxidizing and desulphurizing pyritesof iron containing valuable metals;Fig. 2, a sectional elevation on the linel 2, Fig. 2 Fig. 3, the same011 the line 3 4; Fig. 4., an end view, looking in the direction of thearrow, Fig. 1; Fig. 5, a sectional elevation on the line 5 6, Fig. 1.

Similar letters refer to similar parts through out the several views.

furnace at a point a suitable distance above the fire, and at a slightinclination, is a cylinder or tube, O, on the front end of which is acircular collar having a V-groove adapted to V- shaped rollers d d, thespindles of which revolve on the opposite edges of the trough E, whichis furnished with a supply of water to keep the rollers and theirjournals cool. The cylinder 0, near its opposite end, rests on rollersc, which also revolve in water contained in a trough. A spindle, c, issecured to the end of the cylinder, and is furnished with an ordinaryhandle, by means of which,or by means of any suitable system of gearingconnected with a steam-engine or other prime mover, the cylinder may beturned. From a pulley "on the spindle 0 extends a strap round a similarpulley on the shaft f, which passes longitudinally through and turnswithin the stationary cylin der F, the latter being secured, in aninclined position, to the top and on one side of the furnace. Thisspindle f is furnished with a worm, h, the threads of which fit asclosely as possible to the inside of the cylinder without causing unduefriction.

It will be seen that the stationary cylinder F is situated directlyabove the flue G, through which the products of combustion pass from theoutlet (1 of the furnace to the chimney. cylinder is furnished at itslower end with a hopper, I, and near the latter with an air-opening, t".Near the opposite end of the cylinder is a small tube, j, communicatingwith the chimney, and near the extreme end of the cylinder another tube,k, communicating with the revolving cylinder 0. It will be seen that thelatter is furnished on the inside with spiral ridges or corrugationsextending from end to end. The lower end of this cylinder termi nateswithin and communicates with a vertical box or chamber, .1, (see Fig.5,) to the lower end of which is connected the end k of a steam- .pipe.nicates, through an opening, an, near the top, with another verticalchamber, K, and the latter, through a pipe, n, with a third verticalchamber, L, which is furnished at the top with a tube, M, having anordinary throttle-Valve. Each of these boxes has at the bottom a slidingdoor, for the double purpose of regulating the draft and removing thecontents of the chambers. The quartz and pyrites, having been reduced,as is usual, in a stamping-mill, are first placed on the top of thefurnace, which is provided with retaining-ledges. After the powderedpyrites are dried and partially roasted they are placed into the hopperI, and, dropping from thence into the cylinder F, are carried graduallythrough the latter by the revolving worm until they arrive at the tubek, through which they pass into the revolving cylinder 0. Now, it willbe observed that the stationary cylinder F is submitted to considerableheat by he in g stationed over the flue G, and this heat has the effectof desulphurizing the pyrites, the fumes ofsulphur passing out from thecylinder through the pipej to the chimney. Aidraft is maintained throughthe cylinder by means of the air-hole i, and thus the contents are sub-'This This vertical box or chamber commumitted to a current of air,which, combined with the heat, has the effect of oxidizing the pyrites.After the partially desulphurized and oxidized pyrites pass into therotating cylinder 0, which is immediately over the hottest part of thefire in the furnace, they are agitated by the spiral ribs of, andmaintained in motion during its passage through, the cylinder, thusexposing every particle to the heat, as well as to the current of airwhich passes through the cylinder. The pyrites, now more fullydesulphurized and carbonized, fall from the end of the rotating cylinderinto the box J in aheated condition, and in falling through this box,being brought in contact with a current of air and steam, the latterentering through the pipe 70 and the former through the door at thebottom of the box, are fanned by the current of air, so that thecombustion of whatever sulphur remains will be continued by the oxygenof the air and the oxidizing process by the steam. The heavier particlesof pyrites desulphurized and oxidized by the above process will fall tothe bottom of the box J, while the lighter particles will pass throughthe opening on into the box K, where they meet another current of air,which has the effect of carrying off any remaining fumes of sulphur, theparticles of pyrites falling to the bottom of this box. The still finerparticles will be carried to the third box through the pipe 12, and beacted upon by the air in a similar manner, the remaining fumes ofsulphur, if any, passing through the tube M to the external air. Thedesulphurized and oxidized pyrites are removed at pleasure from thevarious boxes and submitted to any of the amalgamating processes usuallyadopted for separating the valuable metals which are mixed with them. Itwill now be seen that from the time the pyrites are first placed to dryand roast above the furnace until they have passed to the boxes, thedesulphurizing and oxidizing process continues gradually, by beingsubmitted to gradually increasing heat combined with the currents of airand steam. This gradual process is absolutely necessary for effectuallyand rapidly attaining the desired end, inasmuch as a quick and violentheat would tend to cause the sulphur and iron to form a flux, in whichcase the gold or other valuable metal in the pyrites would become sothoroughly embodied that its extraction would be a matter of greatdifficulty.

\Vithout claiming the separate use of the deviccsherein described, Iclaim as myinvcntion, and desire to secure by Letters Patent 1. Thehollow stationary cylinder F, its revolving worm, and its openings forthe admission of the pyrites and the introduction of air and dischargeof the fumes of sulphur, in combination with the rotating cylinder G andits internal ribs, the said stationary and rotating cylinderscommunicating with each other through a pipe, 7;, and the whole beingarranged in respect to the furnace A, substantially as and for thepurpose set forth.

2. The system of vertical boxes or chambers J, K, and L, communicatingwith each other, with the stcanrpipe K, the rotating cylinder 0, and theexit-pipe M, and arranged substantial] y as set forth, and for thepurpose specified.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

- JOHN FRETZ.

Vitn esscs:

HENRY HowsoN, J NO. B. KENNEY.

